Cannabis strength doubles across Europe in 11 years

A study tracking increased potency of both herbal and resin types of the drug points to greater dangers for users
The Guardian (UK)
Sunday, December 30, 2018

Cannabis potency has doubled across Europe in the past decade, according to the first study to track changes in the drug across the continent. The study, published in the journal Addiction and conducted by researchers from the University of Bath and King’s College London, finds that both cannabis resin and herbal cannabis have increased in strength and price with potentially harmful consequences for users. In herbal cannabis, concentrations of THC – the main psychoactive constituent of cannabis which has been linked to psychosis – increased from 5% in 2006 to 10% in 2016. For cannabis resin, THC concentrations remained relatively stable between 2006 and 2011 before increasing rapidly from 10% to 17% between 2011 and 2016.